docs: def get_bounding_box(font):
      """ Returns max and min bbox of given truetype font """
      ymin = 0
      ymax = 0
      if font.sfntVersion == 'OTTO':
          ymin = font['head'].yMin
          ymax = font['head'].yMax
      else:
          for g in font['glyf'].glyphs:
              char = font['glyf'][g]
              if hasattr(char, 'yMin') and ymin > char.yMin:
                  ymin = char.yMin
              if hasattr(char, 'yMax') and ymax < char.yMax:
                  ymax = char.yMax
      return ymin, ymax